Thermochromatic pigment covered article and method of making the same

ABSTRACT

A thermochromatic pigment covered article, comprising a substrate, and a single layer of a combined encapsulated thermochromatic pigment and resin or resin mixture disposed on the substrate. In accordance with the method of the present invention, an encapsulated thermochromatic pigment mixture and a resin or resin mixture are combined and mixed so that the thermochromatic pigment is disbursed and protected in the resin to prevent it from separating therefrom, and the combined pigment mixture and resin or resin mixture are then applied to the substrate in a single layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on and claims the priority ofProvisional Patent Application No. 60/663,738, filed on Mar. 22, 2005,and Provisional Patent Application No. 60/675,464, filed on Apr. 28,2005.

FIELD OF THE INVENTION

The present invention relates to an improved thermochromatic pigmentcovered article and method of making the same. More particularly, thearticle is coated with a single layer of an encapsulated thermochromaticpigment that is contained within a resin in a manner that it does notseparate therefrom.

BACKGROUND OF THE INVENTION

It is known to coat an article such as a mug, teapot or dish withthermochromatic ink such that, when the article undergoes a temperaturechange by, for example, hot liquid being poured therein, an imagedisposed on the article becomes visible as the thermochromatic inkbecomes transparent, and when the article cools, the image “disappears”.Also known are thermochromatic inks that change from opaque totransparent as the temperature changes from hot to cold. With such inks,images can be made to “disappear” when the article is heated.

In some cases, the coated article is covered with a pre-applieddecoration that is covered by the thermochromatic ink coating. In othercases, the coating can be applied to an undecorated article and then adecoration can be sublimated into the coating.

U.S. Pat. No. 5,223,958 to Berry describes a well-known article thatincorporates thermochromatic ink in an amusement device that is heatactivated. Berry's amusement device comprises a supporting substrate, alayer of micro encapsulated thermochromatic liquid crystal materialdisposed on the substrate and an outer transparent film having a messageor visual image. The requirement of a separate layer to carry the image,however, contributes to increased manufacturing costs in terms of bothmaterials and process steps. Moreover, the Berry reference fails toprovide any sort of protection for the transparent film. That is, thetransparent film easily can be damaged by scratching or the like.Moreover still, an article manufactured in accordance with thedisclosure of Berry is deficient in that no protection is afforded whenthe article is subjected to relatively harsh conditions, such as thosepresented by an automatic dishwasher.

U.S. Pat. No. 5,219,625 to Matsunami et al. is similar to Berry anddiscloses a thermochromatic laminate member having a base layer, athermochromatic layer, and a thin transparent iridescent film laminatedon the thermochromatic layer. Color patterns on the film become visibleonce the thermochromatic layer becomes clear after heating. An articlefabricated in accordance with Matsunami et al., however, like an articlemade in accordance with Berry, requires a separate transparent film overthe thermochromatic ink and, further, is susceptible to harshconditions, wherein the laminate and even the thermochromatic ink layercan be damaged.

U.S. Pat. Nos. 6,759,099 and 6,902,775 to Lodge disclose decorationmethods using thermochromic ink wherein a first coating havingthermochromic ink is applied to an article to be decorated, the firstcoating is set or cured, and a second transparent coating material isapplied over the first coating to protect it. This decoration methodrequiring multiple steps and two coatings is time consuming, complicatedand thus expensive.

U.S. Pat. No. 6,281,165 to Cranford discloses a thermochromatic inkcovered article and method making the same wherein a thermochromatic inklayer is disposed on the article, a protective coating is applied overthe thermochromatic ink layer, and a design is disposed at leastpartially in the protective coating. This method is subject to the samedisadvantages as the method disclosed in the Lodge patents in that itrequires multiple manufacturing steps and two coatings to be applied tothe article.

The thermochromatic pigment covered article and method of coating thesame in accordance with the present invention are not subject to thedisadvantages of the articles and methods disclosed in theabove-identified patents, and embody improvements and advantages thatare not disclosed or suggested by the above-identified patents or otherprior art. More specifically, the present invention provides athermochromatic pigment covered article and method wherein only a singlecoating is used that includes an encapsulated thermochromatic pigmentcontained within a resin in a manner that helps to protect the pigmentand prevent the separation of the pigment and the resin.

SUMMARY OF THE INVENTION

In accordance with the present invention, a decorated or undecoratedarticle such as a mug or the like is coated with a single layer ofencapsulated thermochromatic pigment that is disposed in a resin andtreated in a manner to protect it and prevent the separation of thepigment and the resin.

In the method of the present invention, a predetermined amount ofencapsulated thermochromatic pigment in ink, powder or slurry form isfirst mixed together with a suitable wetting or dispersion agent that iscompatible with the pigment so as not to break down its encapsulation.Mixing may be done by hand, mechanical mixer or in any other suitablemanner. During the mixing process, a suitable solvent or solvents and aresin are added to the mixture to disburse or “wet out” and protect thepigment.

Depending on the nature of the resin and the wetting or dispersionagent, a suitable anti-sagging additive may be mixed therewith.

A suitable resin base mixture is then prepared The resin may becomprised of any single or combination of polyesters, acrylics, alkydsor epoxy resin. Also, the resin may be combined with a suitabledurability additive and/or an anti-sagging additive which may include asurface tension additive.

Depending on the type of resin, a crosslinker mixture, which maycomprise a catalyst, solvent and/or crosslinker is added to the resinbase mixture, and these mixtures are further mixed by a mechanical mixeror any other suitable mixing device.

Depending on the substrate or article to be coated, a suitable surfacetension additive may then be added to the final thermochromatic pigmentmixture and resin base mixture after they are combined and mixed, andone or more solvents may be added to bring the combined mixtures to adesired viscosity for spraying or another application process. Anadhesion promoter may then be added to the prepared combined mixture ormay be pre-applied to the article to be coated.

The completed mixture may then be applied as a single layerthermochromatic coating on the substrate or article to be coated. Thethermochromatic coating can be applied to the article by variousmethods, such as by spraying, a waterfall method or dipping. After thearticle is coated, the thermochromatic coating is cured in any suitablemanner such as by heat, air drying or UV exposure. The curing method mayvary depending on the type of resin and other ingredients included inthe thermochromatic coating mixture.

If the coated article is undecorated, it may then be subjected to asublimation process wherein a transfer that is printed with sublimationdyes is applied thereto with suitable heat and pressure to cause thesublimation dyes to vaporize and transfer into the single layer ofthermochromatic coating. After cooling, the transferred image may thenbe obscured by the thermochromatic coating.

Also, in some cases where the coated article is not decorated or printedwith sublimation dyes, it may be screen printed with a design or copy.It may also be screen printed in cases where it is decorated or printedwith sublimation dyes.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an improved thermochromatic pigmentcovered article and method of making the same. Specifically, inaccordance with the present invention, there is provided an article suchas a mug, glass or teapot that can withstand temperature changes and iscapable of “hiding” a design or decoration within a thermochromaticmaterial disposed on the article, and is capable of making the design ordecoration appear when the article is subjected to increased temperatureby, for example, a hot beverage being poured into it. Alternatively, thepresent invention provides such an article that is capable of showing adesign or decoration at room temperature, but may hide the design orsimply just change color when subjected to a cooler temperature by, forexample, a cold beverage being poured therein.

It is to be understood that the present invention is applicable to anyarticle that undergoes temperature changes and on which it might bedesirable to place a design or decoration that appears or disappears orsimply just changes color in accordance with changes in temperature.

In accordance with the present invention, a single layer of a coatingcontaining an encapsulated thermochromatic pigment within a resin isapplied to a decorated or undecorated article. If the article isundecorated, the single layer of the thermochromatic pigment and resincoating may then be subjected to a sublimation process wherein atransfer printed with sublimation dyes is applied to the coated articleand exposed to suitable heat and pressure such that the sublimation dyesvaporize and transfer into the single layer of thermochromatic coating.Also, the coated article may be merely screen printed with a design orcopy, whether decorated or undecorated.

In the new and improved method of the present invention, thethermochromatic pigment is mixed with a resin and other additives in amanner that ensures that the encapsulated thermochromatic pigment isprotected, disbursed in the resin, and does not separate therefrom suchthat it can be applied as a single coating on the decorated orundecorated article to be coated.

According to the method of the present invention, a thermochromaticmixture is prepared by combining a suitable encapsulated thermochromaticpigment in ink, powder or slurry form with a suitable wetting ordispersion agent that is compatible therewith. Depending on the natureof the ingredients, the wetting or dispersion agent may be 1% to 100% byweight of the thermochromatic pigment.

As a specific example, the encapsulated thermochromatic pigment may beDYNA COLOR 45° C. manufactured by CTI, SAKURA COLOR-TC-PB45 manufacturedby Sakura Color Products, or NC BASE Ink manufactured by Matsui. Thewetting or dispersion agent may be K-SPERSE 152 manufactured by KingIndustries.

A desired amount of a suitable resin is added to the pigment and wettingor dispersion agent mixture to “wet out” and disburse the encapsulatedpigment. The resin can be comprised of any single or combination ofpolyesters, acrylics, alkyds or epoxy resin.

The thermochromatic pigment is mixed with the wetting or dispersionagent and the resin by hand, a mechanical mixer or in any other suitablemanner for a period of time, e.g., 1-5 minutes, to effect adequatemixing of the components. While mixing, one or more suitable solventsmay be added to the thermochromatic pigment mixture to vary theviscosity thereof. As illustrative examples, the solvents may be A100manufactured by Sunoco, A150 manufactured by Eastman Chemical, orToluene manufactured by ExxonMobil. The solvents may be added in anamount between 5%-40% by weight of the total thermochromatic pigmentmixture.

Depending on the nature of the ingredients in the thermochromaticpigment mixture, a suitable anti-sagging additive may be mixed therewithin an amount from 5% to 70% by weight of the pigment. Examples ofsuitable anti-sagging additives are as follows:

Name Manufacturer IRCOGEL Lubrizol K-STAY King Industries EASY GEL EagleSpecialty Products

A resin base mixture is then prepared. The resin can be comprised of anysingle or combination of polyesters, acrylics, alkyds or epoxy resin.Depending on the nature of the resin, it may be mixed with a suitabledurability additive and/or anti-sagging additive and, in some cases, asuitable surface tension additive. The components of the resin basemixture may be mixed by hand, with a mechanical mixer or in any othersuitable manner for a suitable period of time and at a suitabletemperature. As illustrative examples, the durability additive may beK-FLEX manufactured by King Industries, the anti-sagging additive may beCERATIX manufactured by BYK Chemie or DISPARLON manufactured by KingIndustries, and the surface tension additive may be BYK361N, an acrylatecopolymer manufactured by BYK Chemie. In the resin base mixture, thedurability additive may be approximately 5 to 10% by weight of theresin, the anti-sagging additive may be approximately 0.5 to 5% byweight of the total mixture, and the surface tension additive may beapproximately 0.05 to 0.5% by weight of the total mixture.

Depending on the type of resin and other ingredients, a crosslinkermixture, comprising a catalyst, solvent and/or crosslinker, may be addedto the resin base mixture, before mixing with the thermochromaticpigment mixture. As an illustrative example, the catalyst may be a PTSAacid catalyst under the name CYCAT 4040 manufactured by Cytec, at a rateof between 0.5% to 3% by weight of the total resin and crosslinkersolids. The solvent may be N-Butanol manufactured by Eastman Chemicals,at a rate of 40% to 60% by weight of the crosslinker, and thecrosslinker may be CYMEL303, a modified melamine resin manufactured byCytec, at a rate of between 20% to 45% by weight of the resin.

The crosslinker mixture and the resin base mixture are mixed in anysuitable manner such as by mechanical mixing. Depending on the resin andother ingredients, a surface tension additive may then be added at arate of approximately 0.05% to 0.5% by weight of the total mixture.

The thermochromatic pigment mixture and resin base and crosslinkermixture are then combined and mixed. Suitable solvents may then be addedto the final thermochromatic pigment and resin base mixture to bring itto a desired viscosity for spraying or for another application process.For spraying, the viscosity may be between 25 and 40 seconds on a Zahmcup No. 2. The solvents may be the same as those used in the pigment andresin mixtures hereinbefore described.

Depending on the nature of the resin and substrate or article to becoated, a suitable adhesion promoter can be added to the total mixturein an amount of between 0.5% to 2% by weight of the total mixture.Alternatively, the adhesion promoter may be pre-applied to the substrateor article to be coated. The adhesion promoter may be a suitable type ofSilane.

The completed mixture may then be used as a single layer thermochromaticcoating to be applied to the substrate or article to be coated in anysuitable manner such as by spraying, a waterfall method, dipping or inany other suitable manner. After the article is coated, a suitablecuring method may be used depending on the type of resin or othercomponents used. As illustrative examples, the coated substrate orarticle may be cured by heat, air or UV radiation for a suitable periodof time.

Before the application of the single layer thermochromatic coating to asubstrate or article, it should be cleaned in any suitable manner tofree it of any dust or contamination.

If the coated substrate or article is not decorated, the decoration canbe applied to the coating thereon by a sublimation process wherein atransfer printed with sublimation dyes is applied to the article andsubjected to suitable heat and pressure for a suitable period of time tocause the sublimation dyes to vaporize and transfer into the singlelayer of thermochromatic coating, as described in the patent toCranford, U.S. Pat. No. 6,281,165.

Because the encapsulated thermochromatic pigment is protected andcontained within the resin mixture so that it does not separatetherefrom, as a result of the new and improved method of the presentinvention, it is not necessary to apply a second protective coating tothe combined thermochromatic pigment and resin mixture. Accordingly,decorated or undecorated articles can be effectively coated by a singlelayer thermochromatic coating in accordance with the present invention.

Specific examples of compositions and the method of the presentinvention are as follows:

Thermochromatic Pigment Mixture

In one illustrative example, approximately 12 to 36 g (preferably about24 g) of K-Sperse 152, a wetting agent manufactured by King Industriesis blended with approximately 500 to 700 g (preferably about 600 g) ofan encapsulated thermochromatic pigment, e.g., DYNA COLOR 45° C., inpowder form by hand or mechanical mixer. Depending on the type andnature of the thermochromatic pigment, the wetting agent may beapproximately 0.5 to 8% of the pigment weight. While continuing themixing, approximately 40 to 120 g (preferably about 60 g) of a solvent,such as A150 manufactured by Eastman Chemical is added to thethermochromatic pigment and wetting agent mixture. Depending on thenature and type of the thermochromatic pigment and the wetting agent,the solvent may be approximately 5 to 20% of the pigment weight.

While the mixing still continues, approximately 300 to 600 g (preferably500 g) of a suitable resin, such as POLYMAC 2882 polyester resinmanufactured by Resolution Specialty Materials, is added to the mixtureand mixed well for approximately 5 minutes. Depending on the nature ofthe resin and the thermochromatic pigment and other ingredients, theresin may be 35 to 100% of the pigment weight.

Thereafter, the thermochromatic pigment mixture is run through a threeroll mill or the like until the thermochromatic pigment powder is wetout thoroughly and the mixture has a glossy appearance. Approximately 2to 15 passes through the roll mill may be necessary. The rollers shouldbe maintained at a temperature below approximately 85% F to preventdamage to the pigment.

The completed thermochromatic pigment mixture is prepared inapproximately 30 to 45 minutes using the above-described steps and canbe stored in any suitable manner until it is ready for use.

Resin Base Mixture

The first part of the resin base mixture may comprise approximately 5500to 5900 g (preferably about 5850 g) of POLYMAC 2882 polyester resin, 700to 950 g (preferably about 900 g) of a suitable durability additive suchas KFlex 188, manufactured by King Industries, and approximately 400 to800 g (preferably about 600 g) of a suitable anti-sag agent such asDISPARLON 6900-20 x, manufactured by King Industries. The resin,durability additive and anti-sag agent are mixed with a mechanical mixerfor approximately 5 to 30 minutes until well blended withoutincorporating any air or a vortex.

Thereafter, while mixing continues, approximately 60 to 130 g(preferably about 100 g) of a surface tension defoamer, such BYK310manufactured by BYK Chemie, is added and the mixing speed is increaseduntil a vortex appears. Depending on the desired viscosity, one or moresolvents may be added to the mixture while mixing continues. Forexample, 300 to 700 g (preferably about 500 g) of A150 solventmanufactured by Eastman Chemical and 300 to 700 g (preferably about 500g) of A100 solvent manufactured by Sonoco may be added.

Finally, approximately 60 to 130 g (preferably about 100 g) of a bubblebreaker or defoamer, surface tension and air release agent, such asBYK323 manufactured by BYK Chemie, is added to complete the first partof the base mixture.

Cross Linker Mixture

Depending on the nature of the resin (e.g., if a polyester resin isused), it may be necessary to add a cross linker mixture to the firstpart of the base mixture. If a cross linker mixture is necessary, oneexample would be to mix in a separate container approximately 1500 to2100 g (preferably about 1960 g) of a stabilizer such as N-Butanol withapproximately 40 to 120 g ((preferably about 60 g) of a catalyst such asCYCAT 4040 manufactured by Cytec, and approximately 2500 to 3800 g(preferably about 3500 g) of CYMEL 303, a crosslinker agent manufacturedby Cytec. This cross linker mixture is mixed until it is well blendedand clear for approximately 30 seconds to one minute. This cross linkermixture is then added to the completed first part of the base mixturewhile mixing continues.

Final Ingredients For Resin Base Mixture

The final ingredients for the resin base mixture comprise approximately80 to 150 g (preferably about 130 g) of a leveling and surface tensionagent such as BYK361N manufactured by BYK Chemie, approximately 200 to400 g (preferably about 300 g) of an adhesion promoter such SILANEmanufactured by Advanced Polymer, Inc. approximately 1500 to 2500 g(preferably about 2400 g) of a suitable solvent such as TOLUENEmanufactured by ExxonMobil and approximately 800 to 1600 g (preferablyabout 1400 g) of a slow solvent such as DB ACETATE manufactured byEastman Chemical for suitable spraying viscosity. These finalingredients are added to the first part of the base mixture and thecross linker mixture while they continue to be mixed together.

Final Mixture

Approximately 400 to 700 g (preferably about 630 g) of thethermochromatic pigment mixture are mixed with approximately 75 to 150 g(preferably about 100 g) of a thermal anti-sag additive such as K-STAY501 manufactured by King Industries. They are mixed with a mechanicalmixer or the like until well blended.

Thereafter, approximately 100 to 200 g (preferably about 120 g) of asuitable solvent such as a A-150 manufactured by Eastman Chemical and100 to 200 g (preferably about 160 g) of another suitable solvent suchas TOLUENE manufactured by ExxonMobil are added to the thermochromaticpigment mixture while mixing continues.

Approximately 1500 to 1900 g (preferably about 1800 g) of the combinedbase mixture and cross linker mixture are then added and mixed with thethermochromatic pigment mixture until well blended. Finally, a slowsolvent such as DB Acetate in the amount of approximately 100 to 200 g(preferably about 160 g) may be added to the final mixture for a desiredviscosity.

Other additives may be used as needed or desired, and other pigments maybe added for different visual effects.

It is noted that the above-described specific composition and method isonly one example of a completed mixture that may be used as a singlelayer thermochromatic coating with use of a specific resin and otheringredients. The ingredients may vary significantly depending on thetype of encapsulated pigment, the type of resin, the type of wettingagent and other ingredients to be used.

Also, in a modified embodiment, the thermochromatic pigment mixture andresin base mixture may be mixed together before the crosslinker mixtureand other ingredients are added thereto and mixed therewith.

While the invention has been described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A thermochromatic pigment covered article, comprising: a substrate; and a single layer of a combined encapsulated thermochromatic pigment and resin disposed on said substrate.
 2. The article of claim 1 wherein said single layer comprises a thermochromatic pigment mixture comprising an encapsulated thermochromatic ink, powder or slurry, and a wetting or dispersion agent mixed therewith.
 3. The article of claim 2 wherein said thermochromatic pigment mixture further comprises a resin mixed therewith.
 4. The article of claim 3 wherein said thermochromatic pigment mixture further comprises an anti-sagging additive mixed therewith.
 5. The article of claim 3 wherein said thermochromatic pigment mixture further comprises a solvent mixed therewith that is compatible with said pigment.
 6. The article of claim 2 wherein said single layer further comprises a resin mixture comprising said resin and a durability additive mixed therewith.
 7. The article of claim 6 wherein said resin mixture further comprises an anti-sagging additive mixed therewith.
 8. The article of claim 3 wherein said resin mixture further comprises a surface tension additive or bubble breaker mixed therewith.
 9. The article of claim 3 wherein said single layer further comprises a crosslinker mixture comprising a catalyst, a solvent and/or a crosslinker.
 10. The article of claim 3 wherein said single layer further comprises an adhesion promoter.
 11. The article of claim 1 wherein said thermochromatic pigment and resin are so combined in said single layer that said thermochromatic pigment is disbursed therein and protected to prevent it from separating from said resin.
 12. The article of claim 1 wherein said substrate is decorated.
 13. The article of claim 1 wherein said substrate is undecorated, and a decoration is sublimated into said single layer. 14-41. (canceled) 